I'd recommend starting with at least one official Arduino so you have a known device to learn how things work, from there...
You can use an Arduino to put a bootstrap loader into other chips. http://www.arduino.cc/playground/BootCloner/BootCloner
The schematics are in the hardware section if you want to make your own Arduino. It is simple enough that you can put it together on a prototyping board. The part that gets complicated is if you want the USB<->RS232 converter. These don't come in DIP packages. I'm not sure if there is one that works at 5V, but I've used a Nokia cell phone data cable in other cases. Some models of these are just USB<->3.3v RS232 converter cables.
If you are cost sensitive and close enough to the US, SparkFun sells the Olimex 28 pin AVR board for $16 (+$4 for an Atmega8) http://www.sparkfun.com/commerce/product_info.php?products_id=29
It is serial interfaced instead of USB and its LED is in a funny spot from the Arduino perspective, but it has a good amount of holes for piecing things together. You'll probably want to put in a 16MHz crystal so you don't have to mess with making a different boot loader image. And you have to connect the RX and TX pins to the level converter on board. Remember to cross them.